Pion Velocity near the Chiral Phase Transition Point in the Vector Manifestation

Abstract

We study the pion velocity near the critical temperature $T_c$ of chiral symmetry restoration in QCD. Using chiral perturbation theory based on hidden local symmetry (HLS) as an effective field theory, where the chiral symmetry restoration is realized as the vector manifestation (VM), we show that the pion velocity for $T \to T_c$ is close to the speed of light, $v_\pi (T) = 0.83 - 0.99$ which is at variance with the sigma model result which predicts $v_\pi (T_c) = 0$. Our prediction on $v_\pi (T_c)$ is compared with the value extracted from the recent RHIC data.